1. Field of the Invention
The present invention relates generally to ion implantation, and more specifically to an apparatus and a method for interlocking a power supply to ion implantation equipment when a voltage difference between a positive and a negative voltage is detected, an apparatus and a method for generating an interlocking signal, an apparatus and a method for interrupting an ion implantation process, and an interlocking system.
2. Description of the Related Art
Ion implantation is a semiconductor process for converting p-type dopant atoms (e.g., boron (B), aluminum (Al), and indium (In)), each of which has three valence electrons, or n-type dopant atoms (e.g., antimony (Sb), phosphorus (P), and arsenic (As)), each of which has five valence electrons, to a plasma ion beam and injecting impurity ions converted from the dopant atoms into a lattice of silicon to form conductors and resistors in a silicon wafer. Ion implantation may be advantageous in that it is relatively simple to control an implantation depth where the dopant atoms are placed in the silicon crystal lattice and to control the concentration of the impurity ions.
Conventional ion implantation equipment may include three systems (e.g., three auxiliary systems). For example, the ion implantation equipment may include an ion source for extracting an ion beam, a beam line for analyzing and adjusting the focus and the energy level of the ion beam, and a target chamber that has a substrate, such as a semiconductor wafer, that is to have ions implanted therein. The target chamber may include an ion dose measuring and controlling system that measures and controls a dose of atoms implanted into a target wafer. In addition, a lens assembly may also be provided to focus the ion beam.
The lens assembly may include a plurality of individual lens assembly units, each of which may have four lenses symmetrically arranged. For example, in each individual lens assembly unit, two of the four lenses may be arranged in a first orientation, e.g., a vertical orientation, and the remaining two lenses may be arranged in a second opposing orientation, e.g., horizontal orientation. The lenses in the individual lens assembly units may be powered by a positive or by a negative power supply. The positive and negative power supplies generate a positive and negative voltage respectively which may be supplied to each of the respective lenses. Lenses symmetrically arranged in the same orientation may be connected to the same polarity power. The power may be supplied to the lenses upon receiving a control signal from a power supply interface unit.
When an error occurs in a connection line that interconnects a power supply interface unit to the positive and negative power supplies, or there is a malfunction in the positive and/or negative power supplies such that voltages are not supplied to the lenses, a focusing error may occur in the beam line. As a result, a size of the ion beam may become enlarged and the ion beam may not pass through a slot provided in a rotating disc in which a target wafer is placed. In addition, the ion beam may not be completely captured in a Faraday cup. Therefore, the enlargement of the ion beam due to the focusing error may result in improperly measuring the dose of atoms implanted into the target wafer.